SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc4c3a7680a27f30366975005f64729ea8a747ce34df3bde788d1f396e480af0' 
  AND token = 'YIKXowREmpVQwcj6AGOkGWRnf9CbZZi7ZwrhJWqkrRo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}